Different type of "coding skills" and different type of complexities make these two impossible to put into the same bucket of "still easy". You've probably never done the latter so you're under impression that it is easy. I assure you it is not. Grasping the concept of a new framework vs doing algorithmic and state of the art improvements are two totally different and incomparable things. In 30M population of software engineers around the globe there is only handful of those doing the latter, and there's a reason for it - it's much much more complicated.